clement



UOC. l5 925 Re. l{6,231

' E. E. CLEMENT Y RADIOPHONE SYSTEM t l original Filed Aug. 14. 1922 5 sheets-'snet 1' Mela/0 Y 1 1 0106157 JUBJ/I 57.0770

"mitm origin fined/Aug. .14. 1922 e sheets-shut 2 Dag-'15, 1925. Re. 16.231

-- E. E. CLEMENT nAnIoPHoNE SYSTEM 6 sheetskslue'I 3 Original Filed Aug. 14. 1922 Dee. 15,1925.`- I 'y A R.`l6.231

E. E. CLEMENT Q RADIOPHO-NE SYSTEM riginal' Film14 Aug. 14. 1922 a` 5 Sheetssht 4 Dec. 15, 1925.` Re. 16,231'

` 4 E. E. CLEMENT I l RADIOPHONE SYSTEM Original Filed Aug. 14. 1922 6 sheetshgdt 5 Dee. 15;l 1925. Re.- 16,2231:

E. E. CLEMENT RADIOPHONE SYSTEM o rigmau Filed Aug. 14. 1922 s sheets-sheet s Ressued Dec. 15, 1925.

UNITE-.n STATES PATENT oFF-ics.

EDWARD E; CLEMENT; or WASHINGTON, DISTRICT oF COTUMBIA, AssIGNoR To EDWARD F.

COILADAY, 0F WASHINGTON, DISTRICT OF COLUMBIA.

RADIOPHONE SYSTEM.

Original No. 1,522,357, dated January 6, 1925, Serial No. 581,829, filed August 1,4, 1922. Renewed July 22, 1924. Application for reissue filed July 7, 1925. Serial No. 42,100.

To all whomfit'mag/ concern:

Be it known that I, EDWARD E. CLEMENT, a citizen of" the United States, residing at VVashington, in the District of Columbia, have invented certain new and useful Improvements in Radiophone Systems, of which the following is a specification, reference being hadA therein to the accompanyingdrawings.,

My invention relates to systems of communication, and particularly to telephone andl radio systems.

following: To organize radio broadcasting service on a'commercial basis, and to controlthe4 service units or receiving' stations so that the various contingencies incidental to commercial operation may be eiciently met,l such as maintenance, supervision, and the imposition and collection of charges; to localize each unitA of a system, so that it may be 'tested andv supervised; to standard- :ize thedistributed unit agencies in a system, while enabling them to receive messages broadcast'ed ony various wave lengths; to control radio broadcasting so that it may supplement` in organized ser-vice existing telephone exchange systems in such manner that the Government, intime of public need,

-unay take oversuch radio broadcasting systems on an organized basis, and operate or supervise the same,\without disturbance of theitelephone service.

Incidental objects are to enable transition, from wired to so-called wireless methodsof communication to lbe accomplished `without substantial changes in practice, or injury toinvestment; andto ensure the proper and natural organization of radio systems when such transition occurs.

The foregoing objects are attained by the method4 of' operation to be hereinafter described, which, it is to be understood, is.

typical, andy is to be taken as such, for purposes of definition and not of limitation of the invention According tothis method I provide a system havingV for its basis thel distribution among regular subscribers in localized areas, of standardized-receiving instruments,.each local area taking its broadcasting service from it'sown central station on such wave lengths as may be fixed land delierrninedf `:for ,that larea.` Each receiving station is connected to the local central station by a wire circuit through which both distribution and the control of the local station are' attained. Vithout being` subject to the limitations of an all-wire telephone system, this arrangement enables me conveniently to feed the substations with current from central for divers purposes, to control the receiving instruments at said stations from the central station, and to meter the. radio service rendered for `the purpose of making charges. Other benets l It has for its objects, among others, the

flowing from this arrangemnt will sulficiently appear from the detailed description hereinafter.

In order to make it possible for subscribersto both send and receive, without technical knowledge and without the necessity for operators licenses, I provide the substation radiophone instrument with means for communicating over the wire circuits to theradio central station, where they may be connected through suitable amplifiers to broadcasting wave transmitters. This attains another object, that is to say, it gives the radio operator supervision and control ofy the message to bey broadcasted as it comes over the telephone circuit, and before it goes onthe Wave transmitter.

The use of individual wire circuits as described, renders it possible to locate each unit and by special means which will be described, to `test and supervise said unit at the substation, as well as to `disconnect and disable the same in case of. necessity.

By using standardized receiving units, all uniformly tuned to the wave length of the local distributing station, I am ableto provide said distributing station with sensitive and powerful receiving and relaying apparatus and circuitsnvliereby distant stations may be picked up, and various wave lengths may be received by variable tuning and their modulations relayed on the standardv local wave length to the subscribers, who can receive and recognize the original messages thus relayed, without the necessity of variable tuning or highly sensitive instruments aty their stations. lith the above arrangement for distribution, by which the ultimate receiving instruments are reduced to the simplest form compatible with their purpose, lI

am veilabled ,t0 eancentrate apparatus requrf i ing lnore elaboration and careful adjustment at the central stations. These are so related to existing high power' broadcasting stations, and to others equipped as a part of the system, that uniform service and uniform programs may be distributed to the local central station according to a regular schedule, and the cost of the primary broadcasting, as well as any special programs put on by the local distributing stations, and the operation of the same will be borne by the subscribers by way of ultimate distribution in individual charges against them.

To control the radio communication in order that it may supplement existing wire agencies, I combine the above described radiophone system with a standard telephone exchange system, locating the standardized radiophone instruments at the telephone subscribers stations, making their wire circuits the existing wire circuits of the telephone system, providing means whereby the use of the radiophone side of the system may be carried on to the fullest extent without interfering with the telephone side of the system, and Without changing any of its circuits or apparatus. The telephone service is given precedence, so that whenever a subscriber is calling or called over his telephone line, all radio connections which might interfere are temporarily broken. From the telephone standpoint, the radiophone instruments may be regarded as extension telephones superimposed on the telephone lines at the subscribers stations, and in a larger aspect the radiophone system as a whole may be regarded as a phantom duplication of the telephone exchange system upon which it is superimposed. It is intended that the two shall be controlled and operated by the same conipany, and since telephone circuits are usu` Vally idle more than 90 per cent of the time,

an opportunity is thus aforded to increase the earnings of the existing physical equipment, as well as to produce substantial earnings on the additional investment required to install the radiophone instruments and switchboards.

This device for controlling and directing the radiophone service over existing lines of organized telephone exchange systems, renders it possible for the Government, in case of need, to take over the radio systems of the country as an organized unit, under trained expert management, and to supervise all transmission thereover without any interference with the general telephone service, and if necessary, without the knowledge of the subscribers thereto. 1 I

It will be apparent after reading the foregoing statement, that my incidental objects are attained as a necessary result of the general organization and arrangement described. The amount of capital invested and to be invested in telephone exchange sys- Y16,231 A v tems in order to meet the demands of service is rapidly increasing, and it is not only highly desirable to increase the earning capacity of the physical telephone plant withouta corresponding increase in the investment, but it is also necessary to forestall independent development of disorganized radio communication systems as well as their illicit or disorderly use.

lVith the foregoing arrangement, the management of and responsibility for the great bulk of the radio apparatus in the country will be placed in responsible hands organized and trained to exercise it etliciently according to law. For the detection of crime, for the general dissemination of intelligence, and to meet emergencies, including the national emergency of war, it is indispensable that such an orderly arrangement be brought about as will regulate the distribution and control of the apparatus, and the systematizing of the radio service on such a basis that it will pay for itself.

No claim is made herein to the method of broadcast distribution disclosed as such, nor to the method of control of the substation radiophone apparatus from central, the same being claimed in a separate copending application, Serial N o. 7 55,574, filed December i2, 192iY My invention is illustratedin the accompanying drawings in which:

Fig'. 1 is a diagram showing tem embodying the same;

Fig. 2 is a diagram showing a central station telephone switchboard, subscribers lines terminating thereon, and subscribers telephones connected thereto;

F ig. 3 is a diagram to be read in connection with Fig. 2, showing the radiophone set at one of the subscribers stations, and the radio switchboard and associated equipment at the central station;

a general sys- Fig. 4 is a diagram showing a substation,r

battery charged and controlled over a phantom circuit imposed on a. metallic magneto telephone circuit;

Figs. 5, 6, 7 and 8 are schematic circuits showing methods of connecting the radio battery with relation to the centralized telephone battery; and

Fig. 9 is a diagram of a modified arrangementof circuits.

Referring to Fig. 1, 1, 2 and 3, represent telephone subscribers stations connected by wires 4, 5 and 6 to the central telephone exchange 7, constituting the distributing center for the area in which local subscribers 1, 2, 3, etc., are located. Superposed upon this telephone system is a radiophone system comprising a central station 8 and subscribers stations 1a, 2a, 3a, etc. The central radio station or exchange is provided with switchboards and a complete broadcasting equipment, and the subscribers stations l, 2, 3,

etc., are provided with receiving instruments all standardized tor the same wave length, and adapted to respond to the waves radiated from the central station 8. The interrelation between the telephone system and the radiophene system is by means of physical connections indicated at 1", 2b, and 3b, at the subscribers stations, and multiples or trunk extensions 15 from the telephone eX- change switchboards to the radiophone exchange switchboard in station No. 8. The detail of these connections will appear hereinafter, but it should be stated here that the system of connections is such that telephone wired traiiic has the right of way over the wires, while the radio traiiic has the right ot way over the radio side of the system. The arrangement is such that the radiooperator cannot interfere with telephone operation, nor can a telephone operator intertere with the radio operation, although under proper conditions each can act freely by .vay of borrowing facilities from the other. At all times, should a question of precedence arise, the apparatus is arranged so as automatically to cut ed the radio connections and to leave the wired lines clear for telephonie use.

Stations 12, 13 and 14 in this figure are typical of inditferently located distant stations which may or may not be a part of this particular system. As the figure is typical only, no attempt has been made to give the geographical location ot' such stations or to show lthe actual arrangement and distribution of the telephone centers through which final broadcasting to the subscribers must take place. The main purpose of this figure is to crystallize the method employed by which the development of a very large number of related individual receiving stations is replaced by an orderly system of distribution through the telephone centers, whereby the individual receiving instruments are localized, maintained, controlled and supplied with definite servicethrough regular channels, for which a definite charge can be made and collected in the manner usual in wired systems of communication. Inasmuch the number et wave lengths available for transmission is limited in the present state ot the art, advantage is taken of the organized system ot' wire distribution and localization to create a phantom system controlled and guided thereby.

Briefly stated, as indicated in Fig. 1, each radio central station er radio department ot a telephone exchange,is not only provided with broadcasting equipment for its subscribers, but also with radio receivers adjustable by timing to wave lengths allotted to such stations as those indicated at 12, 13 and 14, as well as primary stations main.- tained and operated by or under the direcd tion of thetelephone organization itself. By

means understood in the art, messages received at the radio central stations are relayed on their respective standard wave icngths to the local subscribers.

Referring to Figs. 2 and 3, I have therein shown circuits of the central otiice and substation equipments and connections, Fig. 2 representiini` the telephone side ot' the system, and Fig. 3 the radiophone side ot the system. Before proceeding to detail description it may be noted that in accordance with standard telephone practice, provision is made for keeping the telephone lines and. central ofiice circuits clear of all grounds or other disturbing connections during conversation. Vhen the radiophonc goes into service, by closing the filament switch its operation in receiving is identical with that of any radio receiver and `in the event that use is made of any partial transmission of waves over the line wires, as will be hereinafter pointed out, said waves will be at a Yfrequency above or below the limits et audition. In the present diagram, Figs. 2 to 9 inclusive, I have shown the circuits arranged with nothing but continuous current tor radio purposes over the telephone line wires. This is the simplest Jform of control and the one nearest to present day telephone practice, and is absolutely certain not to produce any disturbance in adjacent conductors in the telephone cables. Each radiophone set is provided with a cut eti relay energized when the telephone set goes into commission, either by calling or being called, and at the central olice whenever the radio operator takes control of the line, he disables it in the usual manner by pulling up the cut otf relay `at thetelephone switchboard, this howeverl being subject to the condition that a special tone test may be put on, so that all operators may know that the line is held on the radio board, and subject to interruption for telephone connection. I prefer to use this tone test only with the radio operator-s testing plug, because his regular connecting plug includes within its functions that of connecting a subscriber through the station amplifier to theV broadcasting transn'iitting set, and a connection ot' this character should not be interrupted without permission.

Referring now to the diagrams, Fig. 2, A and A are two subscribers stations connected by line wires 16-17 and 18-19 respectively to theA central station C where they terminate on jacks J and J. P-P are plugs forming the terminals of a cord circuit 20-'21, 22-23, having' a bridged repeating coil 1, ringing and listening keys K and K', Supervisory signals 3&5 and bridging connection to the main battery B. The same battery is shown supplying current to the line relays L, L', and through contacts at the cut off rela-ys L2, L3 to the respective lines for calling purposes. In this system,

when a subscriber takes down his receiver, the line relay lights its lamp, which is eX- tinguished when the operator inserts the answering plug. Battery supply for the connected lines is thereafter taken through the cord circuit 20-22, 21-23, in a manner well understood in the art. lllhen the substation telephones are out of service, with their receivers hanging on their hooks, the line circuits are conductively open for direct current, leaving the ringers Q and Q' in circuit for alternating ringing current passing through the condensers g-Q.

Referring now to Fig. 3 it will be observed that the radio switchboard which I have designated generally by the letter R, is connected to the subscribers lines by multiple taps marked 16a, and 17a, and 17h, and 18, 19, 191. These terminate on multiple jacks lz, J3, corresponding to the multiple jacks on the telephone switchboard. It should be noted that throughout this system the tip Wires 16 and 18 with their branches are connected to ground, while the sleeve wires 17 and 19 and theirbranches, are connected to battery. This is extended into the radio side of the system for the purpose of securing proper balance between the main battery or power plantof that side and the main battery or power plant of the telephone side of the system.

At thesubscribers stations taps are also taken 0H from the telephone terminals to the radiophone termina-ls as indicated at 18, 19, and 19d. (The radiophone is shown only at one substation for sake of simplicity of illustration.) The two branches 19C and 191 are taken from the sleeve or battery side of the line 19, and are connected to opposite terminals of the winding of a relay L4, which constitutes the substation cut ott' relay for the radiophone. The winding of this relay is bridged by a condenser g2 through which both ringing and voice currents can pass without substantial impedance. Where the radiophone is attached to a party line substation, this relay L4 may be omitted, since on such party lines there are usually grounds on one side or the other. As will presently appear, the radio circuits described herein are applicable to two-party or four-party lines, with individual meten ing of the party stations.

Normally, that is to say, when the telephone circuit is not in use, the cut oli' relay L4 is deenergized and as a consequence the wire 19 `is connected through a back contact of the relay through extension wire 24 to the branch 25 connected to the A battery marked A1 in Fig. 3. The wire 18c similarly passes through a back contact of the relay tothe extension wire 26 leading to test or listening relay 27 and ground. 18C, it will be remembered, leads to the tip or ground side of the line, therefore it is the side which in the radiophone can be made use of with a permanent ground or grounds, without disturbing the balance of the telephone circuit.

The radiophone receiver at the substation A' is shown as comprising'an antenna 28, tuned coupler 29, detector tube 30, audio amplifier tubes 31 and 32, and the usual transformers 33, 34, 35, the last mentioned transmitting the amplified audio waves to the telephone receiver or loud speaker 36. The filament b attery is A1. The plate battery is B, and suitable tuning condensers and coils, tickler coil for regenerative ef fects, etc., are provided as required. I should remark in passing that this representation of the radio receiver is intended to be typical only. The present invention does not concern itself specifically with the design of the local radiophone sets, and other circuits and apparatus may be substituted for those shown in the diagrams without departure from the invention.

`The relay L5 has four pairs of contacts, one pair 27a `closing the wires 25 and 37 from battery A1 to the laments. The second pair 27b closes the wires 25 and 38 so as to put battery A1 on the radiophone transmitter T', and through the induction coil I', to ground. The third and fourth pairs of contacts 27C, 27d, close the wires 39 and 40, forming terminals of the secondary induction coil circuit I', to the tip and sleeve side of the telephone line respectiva ly, through the back contacts of relay L4. The transmitter T is shown hanging up on a hook Switch I-I' controlling the connection of wires 41 and 42, constituting a parallel link between the battery A1 and the Filament bus 43. Thus the filament can be heated and the radiophone put in service either through the agency of the relay L, or by the switch hook H. The former is controlled by the radio operator at central, and the latter by the subscriber at the substation. In addition to the hook, the subscriber has a manual switch L by which he can connect the battery wire 42 through a wire 44 to his transmitter T', coil and ground, so as to energize his talking circuit. I provide an ordinary telephone receiver t in series with the secondary of the induction coil I', and I interpose a pair of condensers g3, g4 between the secondary of the induction coil I' and the receiver t on the one hand, and the terminals of relay L5 on the other, so that while the subscriber by means of switch l1, can connect his phone T'-' for receiving calls over the telephone line, he cannot originate calls thereover from the radiophone extension.

Returning now to the central station, and particularly to the radio department thereof shown in Fig. 3, T represents a broadcasting transmitter, symbolized in very simple form, but supposed to contain the usual elements of power' supply, modulator, oscillator and aerial, with suitable amplification ofthe audio waves supplied on' the input side. The jack J4 connected to the amplitier t2 and thence to the transmitter T, symboliZes a group of such jacks or equivalent connecting means such as automatic switches, controlled' by dials or keys for connecting anyof the wire lines to said radio transmitter. Detailed appliances, both for the switching and for the radio transmission, are well known in the art, and need no specific description in this specification, my present invention having to do particularly with the method ot transmitting by wave radiation to the substations,l and of bringing in all conversation originating or received at the substation radiophone over the subscribers wire line. This includes repetition of modulated radio waves received at. the radiophone substation and also`originating messages gathered up and' to be put through the amplier t2 on the transmit-ter T for broadcasting.

It may beexplained here that the transmitter T for general purposes is assumed to be the standard wave length transmitter for the local exchange area, to which all of the substations are tuned and upon which they depend both for original messages and programs and for those received and relayed from a distance. There are special cases, however, in which certain groups of radiophone subscribers may desire intercommunication among themselves, and I contemplate therefore the installation of duplicates of this transmitter, which may be connected up for such group use. For example, a chess club desiring to meet, arranges a program, and at the appointed time its members attend at their radiophones, all removing their transmitters T from their hooks, while the radio operator at the central station plugs up the multiples of their respective lines through their jacks .lL-J3, and connects them on to a special broadcasting transmitter of the type T. This plugging up may be carried out in any desired manner, there being several ways well known in the art for thus connecting telephone lines together. The radio operator then supervises the operation, since any one of the connected subscribers may be speaking through the broadcasting transmitter to the others, and it is necessary to prevent interruption. The same might he said of any meet-ing of a group of people held in this manner, the most valuable feature of this part of the invention being the absolute control afforded over the transmitted messages. The connection to the broadcasting transmitter is solely within the control of the radio operator at the jack J4 or any'other suitable form of switch, and he has 'itin his power therefore to cut o connection at any time. i M,

1 The cord `circuit between plugs P2 and P3 in Fig. 3 is `the same as the operators cord circuit in Fig. 2, but the radiov operator also has special test cords such ras that shown in the upper part of the figure connected to plug P4 for temporary use in testing. Here the keysK-K are of standard construction, as in the other cords, andthe test contact of the plug P* is connected through suitable resistance to the supervisory lamp s2 to the radio battery B means such as the commutator p5 being provided to give special tone test on the test thimbles ofthe multiple jacks J, JQ, J?, etc. It will be observed that `the constant connection of the sleeve or battery .wire 9A at the radiophonel substation to the bus wire 25 of the battery A, producesv charging of that battery by the constant flow of cur,- rent therethrough from the main radio battery B at the central" ottice.. Theamount of energy thusdelivere'd to the battery Al depends upon the size of the line wires, and the length of time available for such charging.` As shown, the battery wire 2st is not cut ott except when thecutotf relay L* pulls up which is only when the line .wire isin use for conversation. `With No.' 19 line wires, and using only the sleeve wire for conduction, it would be possible to .safely transmit from one-half ainperes to two or three ampe'res, according to the line resist-- ance and the voltage of .the bat-tery employed. VVhere this voltage isstandard manual telephone voltage, say 22, and the single wire resistance" to the substation" is from 25 to 50 ohms, it would be possible to maintain the battery A1 `continuously charged, provided the time of discharge be not too long extended, and the charging'be not interrupted by other contingencies, such as the excessive telephone `use of the line. In Fig. 4 of the drawing I show means for charging such a battery' over a phantom netotelephone line. Sucha phamtom circuit of conrsepossesses still lower resistance than a single wireof the pair and correspondingly augments the amount of energy that may bedelivered without a prohibitive loss. I wish to-point out in connection with this, that radio instruments have recently been devised by the commercial radio cori porations, and also by the United States Bureau of Standards, which' employ recv titied lalternating current for lighting the filaments of the audion tubes, 'such 'currents being stepped down to the usual volt-age of the filaments from the voltage of house mains or feederllines. Usingvsu'ch a type of transformer andA 'rectifie'r circuit, it is within the scope otmfy invention', to` ieedl vthe filaments direct, andati vthe 'saine "time vcharge `circuit composed of the two sides of a magl a floating storage battery A, if desired, by transmitting over my line wire 19-19C-24 a sine wave current at such voltage as will deliver the necessary energy.

Connected to the key K is a wire 50 containing a supplemental key lc to connect the voltmeter or other' suitable indicating instrument V and ground. The key K serves to connect the operators listening set, and also to put battery on the tip of the plug, by which means current is thrown out on the tip side 18 of the line, then through extensions 18 and back contact of relay L4 to the winding of relay L5 and ground. The operation of these test keys will be obvious from the description. Key 7c enables the operator to take a reading on the battery A1, the line resistance being known, and the main batteries B, B being disconnected both at the cut oli' relays L3, L7 from the line itself and by the back contacts of key K from the plug P4. This is the most important test because the lamp filaments can be observed by the subscriber, and any defects therein reported over the telephone. A companion test however `enables Athe operator to determinel whether the radiophone instrument as a whole is functioning properly, assuming the transmitter T" to be hung upon its hook H and as shown to have its mouth piece turned toward the emission orifice or diaphragm of the radio telephone receiver. Connection of battery B to the relay L5 causes the sub scribers telephone set T, I, to be connected to line and so to the multiple jack J3, plug Ig and the operators head phone connected through the listening key K. It is assumed of course that some form of broadcasting is going on from the transmitter T, so that the radio-operator not only gets a test on the performance of the individual subscribers radiophone, but also gets a test on his own broadcasting transmitter and on the relative tuning of the same with respect to the subscribers station.

It should be noted that battery B in Fig. 3 is connected to the sleeve wires 17, 19n through the contacts of cut oif relays LG, L7, energized in parallel with the line cut ott' relays L2 and L3 either from the radio board or from the telephone switchboard. This enables the central oilice under all circumstances to keep a talking line balanced and supplied with current only through the connective cord or switch circuits, but as shown in Figs. 5 to 8 inclusive, the connections of the radio battery and that of the main battery are such that the balance is normally maintained, and current is supplied in such a way to the sleeve side of the line that no signaling apparatus on the telephone switchboard is affected thereby.

Fig. 5 shows the condition when a subscriber is talking through the telephone switchboard, the repeating coil I and the main battery B being shown as bridged across the line, and the radio battery B permanently connected through the sleeve side to the subscribers battery A. Battery supply for both the subscribers transmitter and the battery A, would as a matter of fact be drawn in due proportion from each of the centralized batteries B, B', and the resultant effect would be to divide the load between the two parallel sources, without changing the normal condition.

Fig. 6 shows the same arrangement when the subscribers telephone station is idle, and the main battery B is bridged across the line wires between the two windings 1-1 of the subscribers line relay on the telephone switchboard: while the radio battery is connected in parallel to the sleeve side of the line through low resistance choke coils ca a" which do not appreciably reduce the potential placed upon the line terminal of the winding 1 of the line relay, which, being exposed to balanced potentials, will not be energized unless the subscriber calls.

Figs. 7 and 8 show corresponding conditions with the cut ofi' relay L4 at the subscribers station for detaching the battery A, when the subscriber is talking.

It is not considered necessary to actually adopt a permanent connection of the radio battery B because telephone conversations are usually brief and the time of use of the current flow in the sleeve wire would not be thereby greatly curtailed. At the same time, I have provided means in the cut olf relays L6, L7 to disconnect the battery B when the lines are plugged up for conversation as at in Figs. 5 and 7, and when such cut off relays are employed, the choke coils -x may be omitted, so that a practically perfect balance may be had across the terminals of the line relay L. In other words, by using the cut off relays L6, L7, of Fig. 3, I am able to dispense with choke coils ww and connect the battery or charging generator of any type as shown in Fig. 3.

Fig. 9 shows a modified circuit in which the telephone'switchboard and radio switchboard are provided with multiple line connections as before, the radio switchboard iaving connections to the radio broadcasting transmitter T and the radio operator having a full equipment of cords and plugs of known types symbolized at PX. The substation .is provided with a radio detector set and receiver 36, normally connected to the radio detector set through back contacts of the relay L5, which when energized by means of the operators key 7c* at the radio board, will disconnect the receiver 36 and connect the radio detector set on its audio side directly to wires 52-53 and so through the contacts of cut off relay L4 to the line wires 16`17. As there is no battery shown for the detector set (which is typical only), the radio central battery feed is omitted in this figure, which represents a very simple standardized system in which however the radio operator still has perfect` control for all purposes of the substation radiophone. It should be noted that the` continued energization of relay IF disables the radio set, and by winding this relay so as to consume'little current, this atords means to disconnect the subscribers circuit from the radio switchboard until. an insi 'tor can make his rounds and the instrument can be removed.

If it be desired to have no grounds on the radio battery busses at substations, such as that on the A battery at station rfr, in Fim 3, the ground wires may be carried through contacts on switch hook H', opened when the hooks are up.` ).Iany other details of operation may be introduced and changes made, without departing from the scope ot' my invention.

' I claim:

1. A broadcasting system comprising primary high power stations using difieren!I wave lengths, secondary stations having receiving radio setsl 'tunable to the different primary wave lengths and also having relay transmitting apparatus controlled by tne receiving sets and operating on a standard 4fixed wave length the same for all secondary transmitters, and subscribers receiving radio stations, grouped around each secondary transmitting ste. on in its local area and tuned permanently to the lined transmitting wave lengths thereof.

Q. A radio system of interconimunication having a plurality of standardized uniform receiving stations divided into groups, said stations being tuned to one common frequency and of sensitiveness limited to the areas covered by their respective groups, a local transmitting station for each group working on said common wave length, and means for modulating the waves radiated from .said transmitting stations as deter mined by primary stations using variablt wave lengths.

3. The combination of a plurality of sub stations, a central station, a radio broadcasting transmitter at said central station, a radio receiver at each substation, wire line connecting each substation with the central station and telephone on cach line at each substation, with means at the central Station to interconnect the substations for conversation through said wire lines, and means also at said central station supplying operating energy to the radio receivers at the substations over said wire lines.

4. A combined telephone and radiophone system, comprising plurality of substations, a telephone and a radiophone at each substation, a central station common to said snbstations, line wires interconnecting the central .station and the substations, and common means at the central station supplying operating current to both telephones and radiophones over the said line wires, with means at each substation to diicrentiate between the two and to prevent interference.

In a broadcasting system, a main station, a plurality of substations, means at said main station for generating transmitting to the substat-ions radio waves, means at the substaticns for receiving said waves, and individual wire circuits from the main station to the subst-ations, with means the main station controlling the wave receiving means at the substations over said wire circuits. y

6. In a broadcasting system, a main station, a plurality of substatio-ns, means at said main stat-ion for generating and trans mitting to the substations radio waves, means at the substations for receiving said waves, and individual wire circuits from the main station to the substations, with a centralized source oi current supply for the substation receiving means, connected to said wire circuits and distributed thereby to the several substation.

7. A broadcasting system comprising a primary station, a secondary distributing station, and a plurality of local receiving stations related to the secondary station and all in permanent tune therewith, means at said secondary station to receive broadcast waves from the primary station at its wave length, and to relay and redistribute the same in its own area at the standard wave length to which its receiving stations are tuned, and means also at said secondary station to determine when its transmitter is actually tuned to the fixed wave length of its receiving stations.

8. In a radio-telephone system, a transmitting station, a. receiving station, a wave transmitter at the transmitting station for radiating modulated waves, a receiving sot at the receiving station tuned to receive said waves, and a wire circuit connecting the two stations with means to connect it to the receiving set at the receiving station and means to transmit over said wire to the transmitting station modulated current cor responding to the said modulated waves.

9. In a radio-telephone system, a transmitting station, a receiving station, a wave transmitter at the transmitting station for radiating modulated waves, a receivingset at the receiving station tuned to receive said waves, and a wire circuit connecting the two stations with means to connect it to the receiving set at the receiving station, and means at the transmitting station to control said connecting means. y

l0. In a radio-telephone system, a transmitting station, a receiving station, a wave transmitter at the transmitting station for radiating modulated Waves, a receiving set at the receiving station tuned to receive said Waves, and a Wire circuit connecting the two stations With means to connect it to the receiving set at the receiving station, and means at the transmitting station to control said connecting' means through said Wire circuit` l1. In a radio-telephone system, a transmitting station, a receiving station, a Wave transmit-ter at the transmitting station for radiating modulated Waves, a receiving set at the receiving station tuned to receive said waves, and wire circuit connecting the two stations with a source of energy for the receiving set located at the transmitting station and means for feeding said set from said source through said Wire connection.

i2. In aradio-telephone system, a transmitting station, a receiving station, a Wave transmitter at the transmitting station for radiating' modulated Waves, a receiving set at the receiving station tuned to receive said waves, and a Wire circuit connecting the two stations with a source of energy for the receiving set located at the transmitting station and means for feeding said set from said source through said Wire connection as determined at the transmitting station.

13. A broadcasting system comprising one or more primary transmitting stations operating at variable Wave lengths, a localized secondary station having receiving means capable of variable tuning to receive said variable broadcast Waves, and transmitting means connected therewith for relay modulation, but tuned for a iiXed Wave length, and a plurality of receiving stations related to said secondary station by Wire circuits, and having receiving sets tuned to the fixed Wave length of said station, With means controlled by an operator at said secondary station and operable through said Wire circuit to maintain said secondary station transmitting means and said local station receiving sets in constant tune to a common Wave length.

14. The combination of a plurality of substations, a central station, a radio broadcasting transmitter at said central station, a radiov receiver at each substation, a Wire line connecting each substation With the central station and a telephone on each line at each substation, With means at the central station to interconnect the substations for conversation through said Wire lines, and means also at said central station controlling the operation of the radio receivers at said substations over said Wire lines.

15. The combination of a plurality of substations, a central station, a radio broadcasting transmitter at said central station, a radio receiver at each substation, a Wire line connecting each substation with the central to interconnect the substations for conversation through said Wire lines, and means also at said central station for testing' the radio receivers at said substations through said wire lines.

i6, The combination olf a plurality of substations, a central station, a radio broadcasting transmitter' at said central station, a radio receiver ateach substation, a Wire line connecting each substation with the central station and a telephone on each line at each substation, with means at the central station to interconnect the 'substations for conversation through said wire lines, and means also at said central station for connecting and disconnecting the radio receiving apparatus at said substations from said wire lines.

17. The combination of a plurality of substations, a central station, a radio broadcasting transmitter at said central station, a radio receiver at each substation, a Wire line connecting each substation with the central station and a telephone on each line at each substation, with means at the central station to interconnect the substations for conversation through said Wire lines, and means also at said central station for connecting and disconnecting the radio receiving apparatus at said substations from said Wire lines, said means acting automatically to break the radio connections to the Wire line when it goes into service telephonically, and to reestablish the same When said telephone connection is taken down or released.

18. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a Wire line and an ether return or vice versa, and transmitting and receiving means l0- cated at the central station and at the substations, adapted to interrelate the ether Waves and the Wire currents so that modulated radio Waves may be transmitted in one direction, and correspondingly modulated Waves may be returned over the Wire circuit in the other direction.

19. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a vire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether Waves and the Wire currents so that modulated radio Waves may be transmitted in one direction, and correspondingly modulated Waves may be returned over the Wire circuit in the other direction, with means at the central station to control -the transmitting means at each substation.

20. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation',vlof a wire line and an ether return or vice versa, and transmitting and receiving means located atthe central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction, with means at the central stationv to control the receiving means at each substation.

21. A radiophone system of intercommunication comprising a central station, a plurality of substations relatedr thereto, and individual circuits interconnecting thesame, each circuit composed, in operation, ot a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit in the other direction, with means at the central station to control the transmitting and receiving means at each substation.

2Q. A radiophone system of intercommunicationcomprising a central station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composedin operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, `adalitedto interrelate the vether Waves and the wire currents so that `modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit 4in the other direction, with means at the central station to control the substation operation.

Q3. A radiophone system of intercommunication comprising a central station', a plurality of substations related thereto, and

` individual circuits interconnecting the same,

each circuit composed, in operation, of a wire line Aand an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether Caves and the wire currentscso that modu- .ated radio waves maybe transmitted in one direction, `and correspondingly modulated waves may be returned'over the Wire circuit in the other direction, with means at the central station to control the substation operation over said wire lines.

24. A radiophone system of intercommunioation comprising a vcentral station, a plurality of substations related thereto, and individual circuits interconnecting the same, each circuit composed, in operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the Wire circuit in the other direction, with switches at the substations controlling `the relation of received and transmitted Waves, and means at the central station for controlling said switches.

.25.. A radiophone system of intercommunication comprising a central station, a plurality of substations related thereto` and individual circuits interconnecting the same, each eircuit composed, inr operation, of a wire line and an ether return or vice versa, and transmitting and receiving means located at the central station' and at the substations, adapted to interrelate the ether waves and the wire currents so that modulated radio waves may be transmitted in one direction, and correspondingly modulated waves may be returned over the wire circuit inthe other direction.

26. A combined telephone and radiophone system comprising a plurality ottelephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substa-tions, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central station.

27. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to transmit messages kfrom said radiophone central station to its substations by modulated high frequency waves, means at the radiophone. substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephonefcentral station, to-

, gether with means controlled by a telephone llO subscriber in calling to disconnect the Wire connections between his telephone and the corresponding radiophone.

28. A combined telephone and radiophone system comprising a plurality of telephone substations, al telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to'transmit messages from said radiophone central station to its' substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connectio-ns between the radiophone central station and the telephone central station, together with means at each radiophone substation to control the actuating' circuit-s of the radiophone and means also atl said radiophone substations for effecting telephone connection with the corresponding line circuit.

29. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to transmit messages from said radiophone central station to its substat-ions by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central stations, and means controlled by an operator at the radiophone central station to connect and disconnect the wire circuits for telephonie communication between each radiophone substation and the corresponding telephone substation.

30. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnectingI them, a plurality of radiophone substations, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between the radiophone substations and the telephone substations, and wire connections between the radiophone central station and the telephone central station, together with a centralized source of current supply at each of the central stations, both said sources feeding independently through the line wires. to the telephone substations and to the radiophone substations respectively.

3l. A combined telephone and radiophone system comprising a plurality of telephone substations, a telephone central station, line wires interconnecting them, a plurality of radiophone substations, a radiophone central station, means to transmit messages from said radiophone central station to its substations by modulated high frequency waves, means at the radiophone substations to transmit messages telephonically, wire connections between t-he radiophone substations and the telephone substations, and wire connections between the radiophone central Station and the telephone central station, together with a contralized source of current supply at each of the central stations,- both said sources feeding independently through the line wires to the telephone substations and to the radiophone substations respectively, and means controlled by an operator at the telephone central station to disconnect the radiophone central battery from a line when in use for telephonie conversation.

32. A combined telephone and radiophone system comprising a central station and a plurality of subscribers stations with line wires interconnecting them, a telephone switchboard containing connective terminals of said line wires for interconnecting the lines for telephonie conversation, a separate radiophone switchboard containing multiple terminals of said lines, a telephone set and a radiophone set at each subscribers station,

and means'for calling said sets separately from the telephone switchboard and from the radiophone switchboard respectively.

33. A combined telephone and radiophone system comprising a central station and a plurality of subscribers stations with line wires interconnecting them, a telephone switchboard containing connective terminals of said line wires for interconnecting the lines for telephone conversation, a separate radiophone switchboard containing multiple terminals of said lines, a telephone set and a radiophone set at each subscribers station, means at the telephone switchboard for calling the said telephone set, and means at the radio switchboard for calling either set at will.

34. A broadcasting system comprising primary high power stations using different wave lengths, secondary stations having receiving radio sets tunable to the di'erent primary wave lengths and also having relay transmitting apparatus controlled by the receiving sets and operating on a standard fixed wave length and subscribers receiving radio stations grouped around each secondary transmitting station in its local area and tuned to the fixed transmitting wave lengths thereof.

35. A radio system of intercommunication having a plurality of standardized uniform receiving stations divided into groups, all the stations in ecah group being tuned to one common frequency, a local transmitting station for each group working on its common wave length, and means for modulatl l l) broadcast waves from the primary station at .its wave length, and to relay and redistribute the same in its own area to its remitter is actually substations may broadcast and other subscribers outside of the gro-up :may

c eiving stations, and means also at said secondary station to 'determine when its transtuned to a wave length at which its receivingl stations are normally tuned.

37. stations, a central station, a radio casting transmitter at said central station, a radio receiver at each substation, a wire line connecting each substation with the central station and a telephone on'each line at each substation, with'means at the central station to connect a group of said substation telephones to the radio broadcasting transmitter for broadcastingl from said group of substations through said 'transmitter, and means at each of all of said substations for tuning the radio receiver to the broadcasting transmitter, whereby any one or more of the subscribers at said group of among themselves The combination of a plurality of subbroadlistenin at will. 38. A broadcasting system comprising primary high power stations'using different wave lengths, secondary stations having receiving radio sets tunable to the dierent primary wave lengths and also having relay transmitting apparatus controlled by tlie receiving sets normally operating on a given standard wave length and tunable to ay special wave length, and subscribers receiving radio stations grouped around each secondary transmitting station in its local area normally tuned to the given standard wave length thereof and tunable to said special wave length. I

39. A broadcasting system comprising primary high power stations using different wave lengths, secondary low power stations having receiving radio sets tunable to the different primary wave lengths and also having relay transmitting apparatus controlled by the receiving sets normally operating on a given standard wave length, duplicate transmitting apparatus at said secondary stations operable on a wave length different from said given standard wave length, receiving radio sfa e out each secondary station and means at each receiving radio station for tuning the saine to said duplicate transmitter.

40. A broadcasting system comprising a plurality of receiving stationsv all normally tuned to a common given wave length, a transmitting station for: said receiving stations normally working on the said given wave length, means for broadcasting from the transmitting station on a wave length different from saidgiven wave length matter originating at any one or more of a plurality of said receiving stations comprising a sub-group,and means for individually tuning any one of said receiving stations to said second wave length at will.

41. The method of broadcast distribution which comprises primarily transmitting broadcast matter by radiation over a common area at dierent wave lengths, and relaying tlie broadcast matter in different local areas to a plurality of receiving stations in each local area at a frequency common to all the receiving stations.

42. The method of broadcast distribution which comprises receiving broadcast matter at each of a plurality of relay stations. at different wave lengths and retransmitting the received broadcast matter from each relay station to a pluralityT of receiving stations grouped about it in a local area on a frequency common to all the receiving stations of a group.

43. The method of broadcasting intelligence which consists in radiating high power electromagnetic waves for long distances over a large area at different wave lengths, transforming energy so radiated to a plurality of separated points within the large area into low power electromagnetic waves of a definite fixed wave length the same for all the received waves at any one point, and r'reradiating said transformed waves over smaller areas within said large area.

44. The method of broadcasting intelligence which consists in radiating high power electromagnetic waves from a plurality of primary stations by short wave carriers having an identifying energy characteristic for each yprimary station, receiving the energy so radiated at a secondary station for relay'transmission to a group of receiving stations local to the secondary station, changing the received energy into low power carrier waves having an identifying energy characteristic the same for all of the receiving lstations of a group and retransmitting the changed wave at low power over a small area including said group of stations.

45. The method of broadcasting intelligence which. consists in transmitting from a plurality of broadcasting stations to a plurality of receiving stations grouped about each station, original communication on carrier waves having a wave length characteristic of the broadcasting station, receiving at said `broadcasting stations non-original communications on carrier waves having lll-5 different Wave-lengths for the individual non-original communications, and retransmitting the non-original communications at any station on a carrier Wave having the Wave length characteristic or" that station.

46. The method of broadcast-ing over a system comprising tuned receiving stations which comprises transmitting from a primary station to secondary stations, relaying from the secondary stations to receiving stations in a local area on a common Wave length to which the receiving stations are tuned, and controlling the timing from the secondary stations.

47. The method of operating a telephone exchange system to provide broadcast service Which comprises transmitting intelligence. broadcast from the cent-ral otlice to the subscribers stations. and individually transmitting auxiliary operating power to the subscribers stations by current conduction from the central oil-ice.

48. The method ot controlling broadcast service over a telephone exchange system which comprises transmitting modulated Waves from the central office to the subscribers stations by carier current and transmitting the modulations received at the receiving station from the receiving station over the telephone line to the central oirice.

49. The method of broadcasting intelligence Which comprises radiating signal modulated Waves in a path from a transmitting station to a receiving station, conductively transmitting operating'energy in a parallel path from the transmitting station to the receiving station, demodulating said signal modulated Wave at the receiving-station by means of the conductively trans` mitted operating energy, and retransmitting the demodulate'd Wave over said parallel pat-h.

50. The method of controlling radio broadcast distribution which consists in transmitting from one point to another audio frequency modulations oira radio frequency carrier wave, and returning the same modulations to the iirst point as low trequency Waves Without a carrier over a tangible conducting medium.

5l. The method ot controlling radio broadcast distribution which consists in transmitting in one direction through the ether With a return to the transmitting point through a tangible conducting medium, While maintaining proper coordination between the modulations transmitted through the ether and the Waves returned through said medium.

52. The method of controlling radio broadcast distribution Vamong subscribers stationsA from a central point Which consists in transmitting to all said stations in common by means of modulated carri-er Waves,

and returning the same modulations in the tormof coordinated electrical Waves Without a carrier through individual channels to the distributing point.

53. The method of regional broadcast distribution which consists in transmitting F 'cast distribution Which consists in ldistributing broadcast Waves over a common area, conductively and separately supplying operating current from the same distributing point to receiving points in said area, and causing the diverse forms of energy thus supplied to be properlyT coordinated and combined at the receiving points to produce proper reception of the signals transmitte'd.

56. The method of organized radio broad- 'f cast distribution in conjunction Wit-li organized telephonie communication which consists in distributing radio broadcast Waves to subscribers stations from a central station, controlling and supervising the reception of the broadcast Waves over subscribers telephone circuits7 and supplying operating energy for both services over said subscribers circuits, While maintaining the telephonie apparatus irresponsive to the radio currents, and the radio receiving apparatus irresponsive to telephone currents.

57. The method of controlling radio broadcast distribution Which comprises tran sniittin g 1n od ul ated carrier Waves broadcast troni a central station to receiving stations, transmitting the modulations from a receiving` station to the central station, and at the central station adjusting' the relation between the carrier wave frequency and the constants of the circuits at the receiving station to regulate reception at the receiving station.

5S. The method of controlling broadcast distribution to selected subscribers Which comprises 'transmitting radio broadcast from a central station and testing, controlling and metering the reception at the subscribers stations over individual Wired connect-ions from the central office.

In testimony whereof I hereunto my signature.

EDVARD E. CLEMENT.

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